You can use VRay RT for rough visualization, there are three rendering modes you can configure: CUDA, Open CL or CPU. CUDA would be the one that would take advantage of you GPU. My experience with a Quadro 600 gives me no difference between the modes. In any case VRay RT doesn’t support displacement maps and some other features of Vray Production Render.
If you really need the features of Production Render the only way to accelerate render times is to add CPUs. The way to do this is to add render nodes with Vray Distributed Render.